Grinding device



A. A. MARTELL v GRINDING DEVI CE Filed Dec. 51, 1951 2 Sheets-Sheet 1 INVEN TOR.

M 1T m m M v a 0 J wdwx TORNEYS.

Aug. 23, 1932. A. A. MARTELL 1,373;612

GRINDING DEVICE F ild Dec. 51, 1931 2 Sheets-Sheet 2 INVENTOR.

BY [M Mid/x M TTORNEYS.

:UNITED STATES PAT ALBERTA. MARTELL, OF WOONSOCKET', RHODE ISLAND,

substantially then adjusted to present a the use of the bit, and,therefore,

Patented Aug. 23, 1932 ENT "omee nssrelvon r0 MARTELL ii /mun;

racrunme COMPANY, or woou'socxnr, nnonn ISLAND, A conronnmron or mopsISLAND Application filed December 31, 1931. Seria1No.:584,154.

The present invention relates broadly to grinding devices and moreespecially'to a grinding apparatus adapted for grinding detachable bitsfordrilling rock.

Rock drill bits comprise short detachable members adapted to be mountedon the working end of a rock drill and after the bit is dulled to thelimit of its useful life,'it isthe present custom to abandon the pointand replace it by a new one. The present invention contemplatesreclaiming these aban doned points by providing a simple holder for abit which will automatically correctly present the drill faces to agrinding whereby the cutting edges of the drill bit may be restored to auseful condition. Drill bits are made in various sizes and the drillheads are standardized relative to the size of the shank or threadportion of the bit."

For example, one-inch threaded bits are pro vided with drill heads ofthe sizes which differ by eighth inch intervals between the sizes twoand one quarter inches to one and five eighths inches. Other larger orsmaller shanks carry proportionally ranged head It is the purpose of thepresent invenmeans whereby the larger sizes. tion to, provide standardsizes may be ground into the'neXt smaller standard size and thereby,provide doned or discarded drill bits.

the drill bit is locked fixed position in a holder.

in a predetermined This holder is ,adapted to cooperatein definite fixedrelatlon with a tool rest which may be moved toward the face of agrinding wheel at such position and angle as to properly grind one setof faces on a drill bit. The tool rest is 7 new supporting face for thetool holder so that the remaining sides of the drill bit may be groundto provide suitable cutting edges. The ends of the cutting faces areusually worn away during a third tool wheel vention.

increased utility for aban operations' GRINDING DEVICE holding faceprovided-which properly po sitions the side ofthe bit for over-alldimension of the bit to v bringing the outer corners of the faces to theproper sharp formation. In order to faciliing operations, the tool restis tate the grind 7 adapted to be brought against an adjustable grindingthe stop so that the amount of grinding taking place at each operation.is definitely controlled whereby relatively unskilled labor may beutilized for the grindingoperations."

It is recognized that the present inventions may be embodied inconstructions other than those specifically disclosed herewith and,therefore, the present disclosure is-to be understood iting sense. 7

Fig. lis a front elevational view of a grinding wheel with the tool restmounted in front of the wheel to properly addressa drill bit to the faceof the wheel.

Fig. 2 is a side elevational view of the construction shown in Fig. 3 isground in Fig. 1. I 1 a plan view of the face of a bit accordance withthe present insize, thereby} as illustrative and not in the lim- Fig. 4is anelevational view of the bit shown in Fig. 3. y r

5 is an end view of a bit tool holder.

' Fig. 6 is aside view of'the device shown in V Fig. 5. J

Fig. 7 is a plan view of ajig'for setting tool holder prior to thegrinding Fig. 8 is a front shown in'Fig. 7.

Fig. 9 is a cross-section on line 99 of Fig. 2. Referring to thedrawings and more especiallytoFigs. 1 and 2, a grinding wheellelevational View of the jig is mounted upon a spindle 2 which connectswith for rotating grinding wheels. the frame 4 of the grinder may beprovided with a. bracket 5 on which'a supporting arm driving mechanismcommon in the art A portion of sides. ofthe shaft ,.-f the opening 11.

6 issecured by stub bolts 7. This supporting arm 6 carries a supportingshaft 8 which preferably is provided with a shoulder 9 and annut 10carried by the outer end of the sup-' porting shaft 8 is adapted toclamp the shaft tightly in position in the supporting arm 6.

This supporting'shaftS is provided in the forward portion'with'anopening 11 extending axially of the shaft and a pair of slots 12arecu'tlthrough diametrically opposite 8 adjacent the inner end A sliderod 14 is mounted for reciprocating movement in the opening 11 andcarriesacrosspin 15 which passes 1 8. The rotatable sleeve 17 maybe-provided served that through "the, slots 12 and throughdi'ametri cal"opposite sides of astop collar 16 so that when the slide rod 14 is movedendwise in the opening 11, the stop collar is correspondingly slid alongthe'supporting shaft 8. The for wardend of the slide rod 14'is screwthreaded and engages the screw threads in a rotatable sleeve 17whichcarries a. knurled head with an annular groove19 into which theend-of a guidescrew'2O extends so that the rotatable sleeve is.lockedfor rotation in the end ,of the supporting shaft 8. A work rest21 isslidably and normally rotatively mount ed on the outer. end ofthesupporting shaft 8. This work rest is providedwith two pairs ofsupporting faces 22, 24' and 25, 26. Pref- 27. and 28 are arranged onthe supporting faces 22 and 25 adjacent the I erably, stop spins sidenextto the grinding wheell. Theplan es 7 of each pair of thesesupporting faces 22, 24,

and 25, 26 meet at substantially right-angles to receive a substantiallysquare cross-sectiontool'holde'r. The planes of the faces 22, 24

meet in a line that is inclined upwardly relatively to the face of thegrinding wheell and inwardly towardthe axis of this grinding wheel. Theplanes of the faces 25,26 meetin a line that is inclineddownwardlyrelative to the face of thegrinding wheelland "also inwardlytoward theaxis thereof. The

work slide 21 is provided with four keyways 29; 30, 31, and 32, whichareadapted to cooperate with a short key 34 fixedly mounted in thesupporting shaft 8. It will be obby moving the work slide 21 toward theknurled head 18, a sufli'cient distance to clear the short key 34, thatthe work slide maybe rotated on the supporting shaft 8 to bring any oneof the-four keyways into coop eration with the short'key 34. supportingfaces 35, 36 meeting at right angles, are provided on the side of thework slide 21 and it will be noted that the sup porting face 36comprises a'plane which is an- .gularly disposed to the face of thegrinding ,wheel. 1. v

The keyways 29, 30, 31, and '32 areslightly wider than the shortkey 34so that the work rest may be given a limited rotative oscillatorymovement when the grinding is bepositions supporting faces 22, 24; for

A pair. of

wardly on the shaft 8 over ing done to smooth the work, topreventuni-due local wear on the wheel, and also to prevent burning the work.When the respective keyways engage the short key 34, the following workfaces are positioned in operative relation to the grinding wheel; keyway29 grinding one set of faces of the drill bit cutting edges keywaypositions faces 35 and 36 to grind the ends of the cutting edges;keyway- 31 positions the faces 25, 26jto' grind the other set of faces'of'the cutting' edges;

and'keyway 31 holds the work rest in neutral position to permit the useof a. grinding wheel a longitudinal opening 39 coaxial with the axis ofthe tool holder. The shank off the drill bit 37 is adapted to fit theopening 39 and to be clamped there-in means of set screws 40.

Figs. and 8 illustrate jig for correctly the drill bit 37 in the toolholder positioning 38. Tl1lSj1g comprises a base 41 having a crossedopening 42 provided therein. A web 44. extends from one edge of the basein a vertical direction and a guide head extends 1 fromthe web 44substantially parallel to the base 41. The guide head 45 is providedwith 1 an opening 46 which is substantially equal to the cross-sectionaldimensionof the tool holder 38.

In the operation of the device, a drill bit 37 is set on the base 41 ofthe jig with the cutting edges of the bit setting in the crossed opening42 of the jig. The tool holder 38 is slipped into the opening 46- of thejig and over the shank of the drill bit 37 in the jig. The set screws 40are tightened andthe drill bit is now locked in the tool holder-with thecutting edges of the bit definitely positioned relative to the sidesofthe tool holder- The tool holder is now placed against the supporting,faces 22, 24 on the work rest 21 with the forward end of the toolholder'in contact with the stop pin 27, which prevents the drill bitfrombeing drawn into the face of the grind The work rest is now slid foringwheel.

7 the key 34 toward the face of-the rotating grinding wheel 1 land thewheel operates to grind one face of the bit on the angle indicated bytheplaneA of Fig. 4. When the bit is dulled, before the rinding operation,the" cutting edges are ivorn :down to be substantially fiat tops and thefirst grindingoperation is continued until the grinding wheel cuts awaythe metal to substantially the middle part of the dulled flattened edge.When this point in grinding has been reached, the knurled head 18 isrotated to bring the stop collar 16 against the front end of the Workrest, thereby limiting the forward movement of the work rest toward thegrinding wheel. Thetool holder 38 is then turned through 90- with thefront end thereof against stoppin 27 and the work rest is moved towardthe grinding Wheel until stopped by the'stop collar 16, thus grinding asecond face on the drill bit. After the cutting edges have all beenground on one face or side, then the work r'est21 is movedoutwardlytoward the knurlednut 18 to clear faces, 35, 36 and with thekey 34' and the work rest is turned through 180 and then moved inwardlyso that the key 34 now engages the-keyway 31,

thereby bringing the supporting faces 25, 26 into operation. The toolholder as now positioned on the supporting faces '25, 26, is

brought in contact with the stop pin 29 which prevents the work fromsliding into the wheel, and the work holder is moved toward the rotatinggrinding wheel until the work holder is stopped by the collar 16. Thework holder is again turned through and the grinding operation iscontinued to grind the faces indicated by the plane B of Fig. 4.

Even after the fiat tops or edges of the bit have been brought to asharp edge, the outer are usually defaced so that it becomes desirableto grind the bit on the ends of'the edges dimension C shown in Fig. 3. Aproper adjustment for the stop collar 16 is made. The work rest isturned through 90 so that the short key 34 engages the keyway 30,thereby bringing the supporting faces 35 and 36 on top of the work rest.The tool holder 38 is brought into contact with the supporting the endof the tool holder against the stop pin 47. The workrest 21 is now movedtoward the face of the rotating grinding wheel 1 and the ends of thecutting faces on the drill bit 37 are ground away until the work rest 21is stopped by the stop collar 16. This reduces the diameter of the bitto the proper dimension.

It will be observed that the supporting face 36 is angularly disposed tothe face of the grinding'whe'el 1 so that the ends of the cutting edgesof the bit 37 are properly undercut during the grinding operation.

From the foregoing, it will beobserved that the present inventionprovides a rigid, at

comprising a plurality of pairs of supportwork face of the I with agrinding wheel, guiding means, a

ing'surfaces inclined relative to the face. of thegrinding wheel, one ofsaid pair of surfaces being inclined in one direction toward the faceof'said wheel and the otherof said pair of surfaces being inclined inthe opposite direction toward the face of said heel, and

a work holder cooperative with said work rest to wheel.

2. Agrinding present'a drill bit to saidgrinding device f or drill bitsa as;

ing a grinding wheel, guidingmeans, a work rest mounted forreciprocatory movement on said guiding means, an

grinding wheel, said work wheel, one of said pair of c lined in onedirection toward'the face of said wheel and the other of said pair ofsurfaces adjustable stop" to limit the movement of said rest toward therest comprising a e plurality of pairs ofsupporting surfaces inclinedrelative to the face of the grinding surfacesbeing inbeing inclined inthe opposite direction toward the face of said sent a drill bit to said3. A drillbit ing wheel, guiding means, a work rest slidgrinding wheel.

ably and rotatively mounted on said guiding rest having a plurality of;supporting surfaces, a bit holder adapted to cooperate'with thesupporting surfaces on 9 means, said work said work rest to present adrill bit to the workface of the grinding wheel, said bit holder'comprisinga separate block "unattached relative to the work rest, and astop said work rest to to limit the movement of Wards said grindingWheel.

4. A drill bit ing wheel, guiding means comprising a shaft,

a work rest slidably and rotatively mounted a on said guiding means,said work resthaving a plurality of pairs of angularly disposedsupporting surfaces, a bit holder adapted to cooperate with thesupporting said workrest to present a drill bitfto the grinding'wheel, astop to limit the movement of the tool holder on said wheel, and a' Workholder cooperative with said work rest to'pre grinder comprising a grindgrinder comprising a grinds'urfaces on surfaces, and an adjustable stopto'limit the movement of said work rest towards said grinding wheel.

5. A drill bit grinder comprising a grind ing wheel, guiding means, awork rest slid- I ably and rotatively mounted on said guiding means,a'plurallty' of supporting surfaces on sald work rest,'means to retainsaid work rest In a predetermined rotatlve posltlon on said guidingmeans to render a predetermined supporting surface efi'ectlve relatlveto said grinding wheel, a tool holder adapted tohold the drill bit to beground and to cooperate the supporting face'on the work rest to presentcutting edges on the drill bit to the grinding wheel for grinding, andan adjustable stop to limit the movement of said 7 work rest toward thegrinding wheel. I 6. A drill bit grinder comprising a grindmeans torender'a predetermined pair .the supporting face on sent cutting edgeson the drill bit to the grindthrough saidshaftfto adjust said stop. a

ing wheel,

s r on said gulding means, said work rest com-' inclined upwardly andinwardly the drill bit to ing wheel forgrinding, an adjustable stop tolimit the movement'of said work rest toward the grinding wheel, and;means extending 7. A'd'rill'bit grinder comprisinga grindgrinding wheel,a work rest slidably mounted prising a plurality of supporting surfacesangularly disposed to the plane of the face of the grinding wheel, saidsupporting'surfaces being arranged iii-pairs with onejpair of supportingsurfaces meeting at a line which is relative to the plane of rotation ofthe face of the grinding wheel, and another pair of wardly and inwardlyrelative to said wheel face, a work holder adapted to hold a drill bit,said work holder having adjacent sides adj acent surfaces on the work'rest whereby the .sur- 7 of the same angular relation as the faces onthe work holder are adapted to cooperate with the surfaces on the workrestto properly rinding wheel for grinding;

8. A drill bit grinder comprising a grind-- ing wheel, guiding meansadjacent said grinding wheel, a work rest slidably mounted on saidguiding means, a stop to limit the m ovementof vthe work rest, said workrest supporting surfaces meeting at -in a line which is inclinedupwardly and inwardly relative-to the planeof rotation of the face ofthe grinding wheel, awork holder adapted vto hold a drill bit and withthe side 5 a drill bit, meansto position the direction comprising aplurality of supporting surfaces angularly disposed to the plane of theface of the gri ding wheel, said supporting surfaces being arranged inpairs with one pair of a right angle surfaces of said holder meeting atright angles, saidwork holder being an independent block unattached tosaid work rest and with the surfaces on the work holder adapted tocooperate with the surfaces'onthe work restto properly present the facesof a drill bit .to the 'grinding wheel for grinding;

9. Devices for grinding drill bits comprising a tool holder'comprisingan independent block-having supporting side surfaces and with alongitudinal opening to receive guiding means adjacent said,

supporting. surfaces meet ng at a line lnclined downpresent the faces ofa drill bit to the I supportingv of extent of the cutting edges of thedrill bit relatively to thesaid surfaces, a grinding wheel,meanscooperating with said surfaces on the tool holder to present saidcutting edges of the drill bit'to, the grinding wheel a;

to sharpen said edges.

' l0. A grinding device for drill bits com prising a grinding wheel,abracket, a sup:

porting shaft carried by saidbracket, a Work rest mounted forreciprocatorymovement on said shaft, said work rest: comprising aplurality ofpairsof supportingsurfaces- 1nclined relative to the face ofthe grinding wheel, one of said pair of surfaces beinginclined in onedirection toward the face of- I. "said wheel and the other, of said pairof, s-urfaces. being inclined in the opposite direction toward the faceof-said wheel, a work holder having right, angularly disposed surfacesc0--' operating with said workrestvto present a: drill bit to saidgrinding wheel, and means to-guide a drill bit intoa'i definitepredeter-f mined relation to saidwork holder. l 1.--A drill bit grindercomprising a grind-- ing wheel, guidingvmeans, a work rest slidably androtativelymounted on said guiding means, said work rest having aplurality of supporting surfaces, a :bit holder adapted to cooperatewith the supporting surfaces onf said work rest topresent a drill bit tothe work face of the grinding wheel, said bit holder having alongitudinal-opening to receivethe shank of adrill bit, means to set adrill bit in the said opening with the lines of the cutting edges atright'angle's to the surfaces'on the work rest, and a stop to limit themovement. of said work wrest towards said rinding wheel.

12. A drill bit grinder comprising a grinds mg wheel, supporting means,a work rest rotatively mounted on said supporting means, a plurality ofsupporting surfaces on said work rest, means to retain said work rest ina predetermined rotative position on said supporting means to render apredetermined surface'effective relative to said.

grinding wheel, a toolholder adapted to hold I the, drill bit to beground andto cooperate with the supporting face on the work rest topresent cutting edges on the drill bit to the grinding wheel forgrinding, and an adjustable stop mounted on said supporting means tolimit the movement of said work rest to; ,ward the grinding wheel. 1 Y13. A drill bit grinder comprlslng a grind- I ing wheel, a tool holdersupport, a tool holder adapted to hold the drill'bit to be ground, saidtool holder having a longitudinal openingin which the drill bit may berotated, means to set a drill bit into said tool holder with the edgesof said bit set to cause said tool holder to presentcutting edges on thedrillbit to the grinding wheel for correct grinding, means to look th edrill bit in the holder, and an adjust- Qeable stop to limit themovement of said tool holder toward the grinding wheel.

14. A drill bit grinder comprising a grinding wheel, a work restslidably mounted for movement toward and from said wheel, said work restcomprising a plurality of supporting surfaces angularly disposed to theplane of the face of the grinding wheel, means on said work rest todirect a drill bit upwardly and inwardly relative to the planeofrotation of the face of the grinding wheel, and another means on saidWork rest to direct said drill bit downwardly and inwardly relative tosaid wheel face, and stop means to limit the movement of said drill bittoward said grinding wheel.

ALBERT A. MARTELL.

